Some electric shaving apparatuses have at least one perforated shaving foil and at least one undercutter which is constructed to be movable relative to the shaving foil. The shaving foil has a plurality of holes into which hairs thread themselves during the shaving operation. The undercutter is arranged in direct proximity to the shaving foil and is continually moved past the holes of the shaving foil during the shaving operation. As a result, the hairs which thread themselves into the holes of the shaving foil are severed by the undercutter. In this process, the configuration of the shaving foil, in particular the size and shape of the holes, influences the shaving result achievable with the shaving apparatus.
DE 24 55 723 C2 describes an average diameter of the holes in a peripheral region of the shaving foil, which serves at least partly to mount the shaving foil on a shaving head frame, as smaller than an average diameter of the holes in a central region of the shaving foil. In this arrangement, the relationship of the cross-sectional area of the hollow bars separating the holes from each other, which area is measured across the thickness of the shaving foil, to the holes over the complete shaving foil is coordinated in order to achieve a nearly constant flexural resistance. In this way it is intended to design the shaving foil such that it displays a nearly constant flexural resistance over all the perforated regions while retaining stable edge regions and a thin central region.
DE 23 21 028 A describes a screen foil with screen holes of different dimensions, which is adjustably arranged in the shaving head of a dry shaving apparatus. The screen foil has a single undivided perforated zone in which the dimensions of the screen holes change continually in the adjusting direction of the screen foil. This is intended to enable optimum adaptation of the screen foil to the different conditions of facial skin on the user or various users.